The Welsh Liberal Democrats' assembly leader Mike German has warned his party to keep open the possibility of a non-Labour Welsh Assembly Government.

A special Lib Dem conference in Llandrindod Wells on Saturday has put a coalition deal with Plaid Cymru and the Conservatives back on the agenda.

Mr German said the vote on it offered a "once in a lifetime chance to change the way Wales is governed".

An earlier senior party meeting had pulled the plug on the plans.

Mr German's call came a few hours before Welsh Labour leader Rhodri Morgan was nominated to be first minister by assembly members on Friday.

At a news conference in Cardiff Bay, Mr German insisted it was still possible for his party to combine with Plaid Cymru and the Conservatives to oust Labour from power.

A tough period for me

Mike German

But he admitted that the method by which any alternative administration would be formed was unclear.

Mr German said: "A yes outcome will provide a mandate for the programme of government we negotiated with Plaid Cymru and the Welsh Conservative party.

"As to the manner of its delivery, that would need to be reflected upon with the other party leaders after Saturday.

"My message to Wales is this: don't give up on the Welsh Liberal Democrats. The party membership has not yet spoken".

Mr German conceded that "the wheels had come off the wagon" at the Wednesday meeting between the national executive, AMs and negotiating team.

He insisted that the party had an opportunity on Saturday to put them back on.

The suggestion was dismissed by a senior Plaid Cymru figure, who said there had been a "complete collapse in trust" in the Lib Dems.

However a senior Conservative figure intimately involved in the negotiations said that if the Lib Dem conference approved the "rainbow coalition" deal, Rhodri Morgan could face a vote of no confidence before the summer recess.

'Not credible'

Mr German denied that Saturday's vote amounted to a vote of confidence in his leadership.

He said: "It is not about me and I will be saying tomorrow that 'you can dispense with me as a party whenever you like'. It is about the programme for government it is not about me ."

Mr German claimed that 74% of the policies in the deal with the two rival parties came from the Welsh Lib Dem manifesto or were suggested by the party during negotiations.

He said it was not credible for the Lib Dems to refuse to work with other parties when the assembly voting system tended to deny any one party a majority.

Mr German said it was "unbelievable to say we believe in PR (proportional representation) and then can't hack PR when it comes to it".

Reflecting on the previous few days, he admitted they had been "a tough period for me".

Mr German received backing from the Lib Dem leader of Cardiff Council who also leads the party's group on the Welsh Local Government Association

Rodney Berman said: "Surely what matters most to us as Welsh Liberal Democrats is how much of our own policy agenda could be implemented under such a deal?

"Are we really going to pass up on the opportunity for smaller class sizes in our primary schools, or for more uniformed officers on our streets helping make local communities safer?"

'Very bright people'

But former Welsh Liberal Democrat leader Alex Carlile believed the party was right to withdraw from the proposed coalition administration.

Lord Carlile told BBC Radio Wales: "It was obviously tense for those involved but I think it's good for the future of the Welsh Liberal Democrats.

"And I think, above all, actually it produces a much more realistic situation for the assembly".

Asked if Mike German should stand down Lord Carlile said: "That is a matter for Mike German".

"My hope is that there will be a leadership election in the Welsh Liberal Democrats within the next 18 months," he added.

Lord Carlile said there were "lots of very bright people in the party - there are alternative leaders to Mike German".